ATLANTA – Four of every 10 office-based physicians use electronic health records, according to 2009 preliminary estimates by the Centers for Disease Control and Prevention.

The estimates are based on the CDC's National Ambulatory Medical Survey (NAMCS), an annual nationally representative survey of patient visits to office-based physicians that collects information on the use of electronic medical records or electronic health records. A supplementary mail survey was also conducted in 2008 and 2009.

According to the estimates for 2009, 43.9 percent of physicians reported using full or partial EMR/EHR systems (not including systems used solely for billing) in office-based practices. About 20.5 percent reported having systems that meet the criteria of a basic system, and 6.3 percent reported using a fully functional system.

A basic system is defined as having patient demographic information, patient problem lists, clinical notes, orders for prescriptions and viewing laboratory and imaging results. Systems defined as fully functional also include medical history and follow-up, orders for tests, prescription and test orders sent electronically, warnings of drug interactions or contraindications, highlighting of out-of-range test levels and reminders for guideline-based interventions.

The survey indicates that from 2007-2008, physicians' use of any EMR system increased by 18.7 percent and the percentage of physicians reporting having systems that meet the criteria of a basic system increased by 41.5 percent. Researchers conclude that the 2009 preliminary estimates did not change significantly from 2008.

Researchers say data from the 2009 NAMCS will be combined with the mail survey to obtain a final 2009 estimate.